Electric grounding switch



March 6, 1962 T. A. BURDESHAW ELECTRICGROUNDING SWITCH 2 Sheets-Sheet 1Filed' Jan. 27, 1960 IOA INVENTOR. THOMAS A. BURDE S HAW FIG. 2

FIG. 3 WW/? 771 W ATTORNEY March 6, 1962 T. A. BURDESHAW 3,024,328ELECTRIC GROUNDING SWITCH Filed Jan. 27, 1960 2 Sheets-Sheet 2 7' Hg 3xINVENTOR.

THOMAS A. BURDESHA W ATTORNEY United States Patent 3,024,328 ELECTRIC GOUNDING SWITCH Thomas A. Burdeshaw, Hampton, Ga., assignor to SouthernStates Inc., a corporation of Georgia Filed Jan. 27, 1960, Ser. No.4,939 2 Claims. (Cl. 20087) This invention relates to electric groundingswitches and more particularly to grounding switches which areparticularly adapted for quick and easy operation.

A prime requirement for electric grounding switches is that they operateat extremely high speed to ground an associated circuit in order thatmaximum protection may be afforded to the circuit and to apparatusconnected therewith. In order to achieve high speed operation it hasbeen the practice to impart high speed movement to the movable switchelement and to construct the fixed switch element in such a way that thefixed element is capable of arresting high speed closing movement of themovable contact and of absorbing its kinetic energy without damage. Whenthe fixed contact is so constructed it is difiicult to open the switch.Furthermore, it is not practical to construct a grounding switch whereinthe blade is swung into the space between the jaws of a jaw contact andthereafter rotated about its axis so as to establish high pressurecontact. Such operation is not feasible in grounding switches becausethe time available is not sufiicient to accommodate such complicatedoperation.

A principal object of this invention is the provision of a groundingswitch which is capable of high speed closing and which is also easy toopen.

Another object of this invention is to provide a high speed groundingswitch which is protected against damage due to arcing by the use ofmagnetic means for maintaining high contact pressure after the switch isclosed.

The invention in one form as applied to a high speed grounding switchcomprises a fixed contact, a movable contact constructed of two parts,one of such parts being a contact bearing part and the other being amotivating part arranged in articulated relation with the contactbearing part, motivating means interrelated operably with the contactmotivating part, the contact bearing part and the motivating part beingarranged to impart swinging movement to the contact bearing part duringswitch closing and the articulated relation between the parts being suchthat opening movement is achieved by substantially axial movement of thecontact bearing part during switch opening. Thus the fixed contactstructure can be constructed using magnetic means and other means, ifdesired, to arrest high speed closing movement of the movable contactand so as to afiord a minimum of resistance to opening movement of themovable contact relative to the fixed contact structure.

For a better understanding of the invention reference may be had to thefollowing detailed description taken in conjunction with the drawings inwhich FIG. 1 is a side view of an electric grounding switch embodyingthe invention and showing the switch in the closed position; FIG. 2 is aView similar to FIG. 1 and showing the parts in the position they occupyduring opening of the switch but before the switch contacts areseparated; FIG. 3 is a view similar to FIGS. 1 and 2 and showing theswitch in the fully open position; FIG. 4 is an enlarged side Viewpartially in section of the upper end of the switch depicted in FIGS.l-3; and in which FIG. 5 is an enlarged side view partially in sectionof the lower end of the switch depicted in FIGS. 1-3.

With reference to FIG. 1, the numeral 1 designatm supporting structureon which an insulator stack 2 is securely afiixed. Mounted atopinsulator stack 2 is a fixed contact structure generally designated bythe numeral 3.

3,024,328 Patented Mar. 6, 1962 Arranged in cooperative relation to thecontact structure 3 is the movable contact blade generally designated bythe numeral 4. The contact blade 4 is operated by motivating meansgenerally designated by the numeral 5 and which is shown schematically.Motivating means 5 is provided with a drive shaft 6 on which a drivinggear 7 is secured. Gear 7 meshes with pinion 8 which is secured to androtatable with a pin 9 on which the movable contact blade 4 is pivotallymounted. As will be more fully explained hereinafter, the blade 4 isformed in two parts. One such part designated by the numeral 10 is acontact bearing part and the other such part designated by the numeral11 is a motivating part. The parts 10 and 11 are pivotally connected bya pin 12. Contact bearing part 10 is provided with a contact element 13which is engageable with and disengageable from a fixed contact 14secured to fixed structure 15 which in turn is mounted on the supportelement 1. As will be understood, the element 1 is provided withsuitable grounding connections not shown. Furthermore, it will beunderstood that the fixed contact structure 3 is interconnected bysuitable means, not shown, with a circuit which is desired to begrounded upon the occurrence of fault or other conditions.

From the description thus far it will be understood that upon theoccurrence of a fault in the circuit protected by the grounding switchmotivating means 5 operates upon sensing the fault condition to drivegear 7 and pinion 8 in such a direction as to swing the blade 4 from theposition depicted in FIG. 3 to that depicted in FIG. 1 at high speed. Inthis manner a ground circuit is established from the fixed contact 3through blade 4, contact 13, contact 14, element 15 and structure 1which, as already explained, is grounded.

In order to open the grounding switch after the establishment of aground, motivating means 5 is reversed and rotates the gear 7 in adirection opposite from that in which the gear is rotated duringclosing. Such operation imparts clockwise motion to motivating part 11of blade 4 and causes the articulating pin 12 to swing in a clockwisedirection about the pivot 8. Such move ment causes the parts to assumethe positions depicted in FIG. 2. Thereafter continued rotation of pin 9in a clockwise direction swings the pin 12 downwardly and toward theright and separates the movable contact 10A mounted atop the contactbearing part 10 from the fixed contact structure 3 and as the motioncontinues the parts eventually occupy the positions depicted in FIG. 3.

The details of construction of the fixed contact structure are bestshown in FIG. 4. With reference to that figure, it will be understoodthat the contact bearing element 10 is provided with a part 16 which isengageable by a latch 17 pivotally mounted on the pin 18 and biased bythe spring 19 toward rotation in a clockwise direction about the pivot18 to a position of engagement with a stop 20. Thus it will beunderstood that closing of the contact bearing element 10 causes the pin16 to engage the surface 19A of the latch 19 and to swing the latchmomentarily in a counterclockwise direction until the pin 16 moves underthe latch tip 19B. Thereafter, with the contact bearing part 10 in theposition shown in FIG. 4 the latch 17 moves in a clockwise directionabout the pin 18 due to the bias of the spring 19. Thus it will beunderstood that once the contact bearing element 11 is swung into theposition depicted in FIG. 4 the latch 17 latches and prevents swingingmovement of contact bearing part 10 in a direction opposite to that inwhich the part 10 is moved during closing of the switch.

In order to insure positive contact between the movable contact 10A andthe fixed contact structure 3, magnetic means are provided. Such meansmay comprise a loop element 21 afiixed at one end by the bolts 22 andthe clamping bar 23 to the fixed structure 24. In addition, the loop 21is anchored by a screw 25 to fixed support structure 26. The free end ofthe loop 21 designated by the numeral 27 is biased downwardly by meansof a plunger 28 which abuts pad 27A and a compressional spring 29, theupper end of which is in engagement with the combination corona shieldand sleet hood 30 and the lower end of which is in engagement with adisc 31 which is secured to the plunger 28. Thus bias of spring 29exerts a downward force on the disc 31 and the plunger 28 and in turn onthe free end 27 of the loop element 21 via pad 27A. The free end 27 ofloop 21 is arranged to engage contact 10A which is mounted on the uppertip of the contact bearing part 10. Thus with the parts in the positiondepicted in FIG. 4, current flowing through loop 21 urges the free end27 of the loop 21 in a generally downward direction due to the expandingaction of the magnetic loop. This force, together with the force ofbiasing spring 29, combine to provide a downward force greater than theforce tending to separate the free end 27 of loop 21 from the movablecontact 10A due to the effect of the current flowing from contactbearing part 10 angularly outward along the free end 27 of the loop.Thus the contact 10A and the free end 27 of loop 21 are maintained in asecure contact making relation.

Of course if no current is flowing the contacts will be held closed bythe bias of spring 29.

The lower portion of the switch is best shown in FIG. 5. As can best beseen in FIG. 5, the pivot 12 interrelates the contact bearing part 10and the motivating part 11 of blade 4 and in addition, the motivatingpart 11 is provided with an abutment surface 33 which engages a stop 34forming an integral part of contact bearing part 10. Thus whencounterclockwise moment is imparted to motivating part 11 by pivot 6 thestop 34 engages the abutment surface 33 and the entire blade 4comprising contact bearing part 10 and motivating part 11 swings rigidlyas a unit and the upper end of blade 4 chops in to occupy the positiondepicted in FIG. 4. Furthermore, it will be understood that the contact13 mounted on contact bearing part 11 engages the contact 14A which isbiased downwardly by a spring 14B toward engagement with the contact 13.

When it is desired to open the switch clockwise moment is imparted topin 6 by the motivating means and the motivating part 11 swings in aclockwise direction about the pin 6. This causes the pin 12 to swing inan arc clockwise about pivot 6 so that the stop 35 engages the abutmentsurface 36 and allows the contact bearing part to move generally axiallydownward to open the circuit. During opening the pin 16 disengages latch17 and contact 10A separates from the free end 27 of loop 21.

While I have shown and described a particular embodiment of theinvention, I do not wish to be limited thereto and intend in theappended claims to cover all such changes and modifications as fallwithin the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electric switch comprising fixed contact structure, a tubularmovable contact, and means defining a loop circuit having a fixed endsecured to said contact structure and having a free end biased towardengagement with an end of said movable contact, the direction of thebias being in substantial coincidence with the longitudinal axis of saidtubular contact and the magnetic force of said loop circuit and theforce of the bias of the free end thereof being generally opposite toand greater than the force imparted to said free end due to theconfiguration of the circuit comprising said tubular contact and saidfree end of said loop circuit so as to maintain said free end of saidloop circuit in secure engagement with said end of said movable contact.

2. An electric switch comprising fixed contact structure, a tubularmovable contact, arranged to move in one general direction duringclosing of the switch and in a direction generally transverse theretoduring opening of the switch, means defining a loop circuit having afixed end secured to said contact structure and having a free end biasedtoward engagement with an end of said movable contact, the magneticforce of said loop circuit and the force of the bias of the free endthereof being generally opposite to and greater than the force impartedto said free end due to the configuration of the circuit comprising saidtubular contact and said free end of said loop circuit so as to maintainsaid free end of said loop circuit in secure engagement with said end ofsaid movable contact, and a latch mounted on said fixed contactstructure and biased toward a position of engagement with a part of saidmovable contact, stop means for limiting the travel of said latch due toits bias, said latch being eiiective to engage said part of said movablecontact during a switch closing operation and to prevent movementthereof in a direction opposite to the direction of closing movement butbeing ineffective to prevent opening movement in a direction generallytransverse to the direction of closing movement.

References Cited in the file of this patent UNITED STATES PATENTS1,843,415 Johnson Jan. 3, 1933 1,949,018 Koppitz Feb. 27, 1934 1,958,159Bresson May 8, 1934 2,626,332 Earle et al. Jan. 20, 1953 2,695,350Schultz Nov. 23, 1954 2,759,076 Curtis Aug. 14, 1956 2,840,671 GiefiersJune 24, 1958

